#include <stdio.h>
#include <stdlib.h>
struct flex_array_struct{
    size_t num;
    int data[];
};
void print_array(struct flex_array_struct *struct_p){
    puts("Array is: ");
    for (size_t i = 0;i < struct_p->num; ++i){
        printf("%d ",struct_p->data[i]);
    }
    putchar('\n');
}
void func(void){
    struct flex_array_struct *struct_p;
    size_t array_size = 4;
    /* Space is allocated for the struct and initialized... */
    print_array(struct_p);
}